Hypertrophic Cardiomyopathy
Hypertrophic cardiomyopathy is a primary disease of cardiac muscle characterized by left ventricular hypertrophy and disproportionate, asymmetrical thickening of the intraventricular septum, particularly in the anterosuperior aspect. It’s also distinguished by a dynamic left ventricular outflow tract pressure gradient. This is related to the narrowing of the subaortic area caused by the septal hypertrophy in the mitral valve area. The obstruction
produced may change between examinations and even from beat to beat.
produced may change between examinations and even from beat to beat.
In hypertrophic cardiomyopathy, cardiac output may be low, normal, or high, depending on whether stenosis is obstructive or nonobstructive. Eventually, left ventricular dysfunction—a result of rigidity and decreased compliance—causes pump failure. If cardiac output is normal or high, the stenosis may go undetected for years, but low cardiac output may lead to potentially fatal heart failure.
The course of this disorder varies. Some patients demonstrate progressive deterioration, whereas others remain stable for several years.
Causes
About half of all cases are transmitted as an autosomal dominant trait. Other causes aren’t known.
Complications
Pulmonary hypertension and heart failure may occur secondary to left ventricular stiffness. Sudden death is also possible and usually results from ventricular arrhythmias, such as ventricular tachycardia and premature ventricular contractions.
Assessment
Generally, clinical features don’t appear until the disease is well advanced. At that point, atrial dilation and sometimes atrial fibrillation abruptly reduce blood flow to the left ventricle. Most patients are asymptomatic but have a family history of hypertrophic cardiomyopathy. In some instances, death occurs without warning, particularly in children and young adults. Patients who have symptoms complain of dyspnea on exertion. They commonly have anginal pain, fatigue, and syncope.
Inspection of the carotid artery may show a rapidly rising carotid arterial pulse. Palpation of peripheral arteries reveals a characteristic double impulse (pulsus biferiens). Palpation of the chest reveals a double or triple apical impulse. Percussion may reveal bibasilar crackles if heart failure is present. Auscultation reveals a harsh systolic murmur, heard after S1 at the apex near the left sternal order. The murmur is intensified by standing and with Valsalva’s maneuver. An S4 may also be audible.
Diagnostic tests
